At present, Asynchronous Transfer Mode (ATM) technology is being developed to provide broadband switching capability for telecommunications calls. A call is a request for telecommunications services. Some ATM systems have used ATM cross-connects to provide virtual connections. Cross-connect devices do not have the capacity to process signaling. Signaling refers to messages that are used by telecommunications networks to set-up and tear down calls. Thus, ATM cross-connects cannot make connections on a call by call basis. As a result, connections through cross-connect systems must be pre-provisioned. They provide a relatively rigid switching fabric. Due to this limitation, ATM cross-connect systems have been primarily used to provide dedicated connections, such as permanent virtual circuits (PVCs) and permanent virtual paths (PVPs). But, they do not provide ATM switching on a call by call basis as required to provide switched virtual circuits (SVCs) or switched virtual paths (SVPs). Those skilled in the art are well aware of the efficiencies created by using SVPs and SVCs as opposed to PVCs and PVPs. SVCs and SVPs utilize bandwidth more efficiently.
ATM switches have also been used to provide PVCs and PVPs. Since PVCs and PVPs are not established on a call-by-call basis, the ATM switch does need to use its call processing or signaling capacity. ATM switches require both signaling capability and call processing capability to provide SVCs and SVPs. In order to achieve virtual connection switching on a call by call basis, ATM switches are being developed that can process calls in response to signaling to provide virtual connections for each call. These systems cause problems because they must be very sophisticated to support current networks. These ATM switches must process high volumes of calls and transition legacy services from existing networks. An example would be an ATM switch that can handle large numbers of POTS, 800, and VPN calls.
Currently, ATM multiplexers are capable of interworking traffic of other formats into the ATM format. These are known as ATM interworking multiplexers. ATM multiplexers are being developed that can interwork traffic into ATM cells and multiplex the cells for transport over an ATM network. One example of an application of these muxes is provided by T1 transport over an ATM connection. Traffic that leaves the switch in T1 format is muxed into ATM cells for transport over a high speed connection. Before the cells reach another switch, they are converted back into the T1 format. Thus, the ATM mux is used for high speed transport. The ATM mux is not used to select virtual connections on a call-by-call basis. Unfortunately, there is not a telecommunications system that can provide ATM switching on a call by call basis without relying on the call processing and signaling capability of an ATM switch.
One solution to the above-described problems is disclosed in the parent applications cross-referenced above. This application disclosed the call by call control of the interworking point. The present invention provides enhancements and improvements to those systems.
The invention includes a method of operating a telecommunications system to provide a call with a virtual connection. The invention is applicable where a user places the call by sending signaling for the call to the telecommunications system and by transmitting user information to the telecommunications system over a particular connection for the call. The telecommunications system comprises an ATM interworking multiplexer and a signaling processor coupled to the ATM interworking multiplexer. The method comprises receiving the signaling for the call into the signaling processor and processing the signaling to select the virtual connection. The method further includes generating a control message in the signaling processor to identify the particular connection and the selected virtual connection, and transmitting the control message to the ATM interworking multiplexer. The method further includes receiving the user information for the call from the particular connection into the ATM interworking multiplexer and converting the user information into ATM cells that identify the selected virtual connection in response to the control message. The method further includes transmitting the ATM cells from the ATM interworking multiplexer over the selected virtual connection.
The invention also includes a telecommunications system to provide a call received over a particular connection with a virtual connection in response to signaling for the call. The telecommunications system comprises a signaling processor operable to receive and process the signaling to select the virtual connection for the call, and to generate and transmit a control messages that identifies the particular connection and the selected virtual connection. The system further includes an ATM interworking multiplexer operable to receive user information from the particular connection, convert the user information into ATM cells that identify the selected virtual connection in response to the new signaling, and to transmit the ATM cells from the ATM interworking multiplexer over the selected virtual connection. The invention further includes a means for coupling the signaling processor and the ATM interworking multiplexer that is operable to transfer the control message from the signaling processor to the ATM interworking multiplexer. In some embodiments the system also includes an ATM cross-connect system connected to the ATM interworking multiplexer and configured to provide a plurality of virtual connections to the ATM interworking multiplexer.
In various embodiments, the invention accepts calls placed over DS0 voice connections and provides virtual connections for the calls. In this way, broadband virtual connections can be provided to narrowband traffic on a call-by-call basis without requiring the call processing and signaling capability of an ATM switch.